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Low vitamin D levels linked to multiple sclerosis

December 3, 2012

People with high vitamin D blood levels may have a decreased risk of developing multiple sclerosis, suggests a new Swedish study.

In the observational study, the vitamin D concentrations of blood samples from 164,000 participants – the majority pregnant women – living in northern Sweden were measured and those who developed multiple sclerosis (MS) were documented (1). The blood samples of people who developed MS were matched with at least two control samples of healthy people collected on the same date. The study results showed that parti-cipants with the highest blood levels of vitamin D (above 30 ng/ml) were 61% less likely to develop MS over an average period of nine years than people with lower vitamin D levels. No protective effect was observed for children whose mothers had higher vitamin D levels during pregnancy.

The researchers commented that this lack of evidence for protective effects of vitamin D consumption during early pregnancy suggests that its protective effects may play a role later in pregnancy and beyond.

Another study compared birth data from 151,978 MS patients in countries located at various distances from the equator, with the variable being that people living in countries closer to the equator would get natural sunlight for longer periods during the year (2). The study found a significant increase in MS risk in babies born in April and May and a significantly lower risk among those born in October and November. The results suggest that women who gave birth in autumn, after having enjoyed sunlight during the summer months while pregnant, actually lowered their risk of having a baby who would later develop the disease.

The researchers concluded that vitamin D supplementation is necessary in pregnant women who live in countries where ultraviolet light levels are low between October and March, conditions that are similar to living in the northern U.S. states during the winter.

References

  1. Salzer J. et al. Vitamin D as a protective factor in multiple sclerosis. Neurology. 2012; 79(21): 2140–2145.
  2. Dobson R. et al. The month of birth effect in multiple sclerosis: systematic review, meta-analysis and effect of latitude. J Neurol Neurosurg Psychiatry. Published online November 2012.